A cubic boron nitride sintered body (hereinafter usually referred to as “cBN sintered body”) has excellent wear resistance and is therefore used as, for example, cutting tools. In particular, the cBN sintered body is widely used to machine cast iron and sintered alloys that are difficult-to-machine materials. For example, Patent Document 1 discloses a cBN sintered body that is composed of a cubic boron nitride (cBN) phase and a binding phase containing W, Co, and Al, and contains B6Co21W2 at a predetermined ratio as the binding phase. Patent Document 2 discloses a cBN sintered body that contains 80% by weight or more of cBN particles and Al whose content ratio exceeds 50% by weight. The Al is added together with Co as a binding phase.